Heat exchanger with a removable tube section

ABSTRACT

A heat exchanger in which the tube sheet is secured against primary liquid pressure, but which allows for easy removal of the tube section. The tube section is supported by a flange which is secured by a number of shear blocks, each of which extends into a slot which is immovable with respect to the outer shell of the heat exchanger.

United States Patent 11 1 Wolowodiuk et al.

1 1 July 29, 1975 1 1 HEAT EXCHANGER WITH A REMOVABLE TUBE SECTION [75] Inventors: Walter Wolowodiuk, New

Providence; John Anelli, Pa'rsippany, both of NJ.

[73] Assignee: The United States of America as represented by the United States Atomic Energy Commission, Richland, Wash.

[22] Filed: May 1, 1972 [2]] Appl. No.2 248,922

[52] U.S. Cl. 165/76; 165/158; 165/162; 7 285/111 [51] Int. Cl. F28b 7/00 [58] Field of Search 165/158-162, 165/76; 122/32, 510; 285/138, 111, 141

[56] References Cited UNlTED STATES PATENTS 1,757,724 5/1930 Larson 285/111 X 2,857,142 10/1958 Gertzon 165/158 3,424,480 l/l969 Holland 285/1 1 1 3,526,275 9/1970 Vance et a1 165/158 3,656,543 4/1972 Wolowodiuk 122/32 Primary Examiner-Manuel A. Antonakas Assistant ExaminerTheophi1 W. Streule, Jr. Attorney, Agent, or Firm-John E. Wilson; Marvin A. Naigur [57] ABSTRACT A heat exchanger in which the tube sheet is secured against primary liquid pressure, but which allows for easy removal of the tube section. The tube section is supported by a flange which is secured by a number of shear blocks, each of which extends into a slot which is immovable with respect to the outer shell of the heat exchanger.

5 Claims, 3 Drawing Figures PATENTEI] JUL 2 9 I975 SHEET PATENTEDJUL29IH75 3,896,873 SHEET 2 72 60 M; l 2 m 2 V V & A a4 e4 SOURCE OF THE INVENTION This invention was made in the course of or under a Contract with the US. Atomic Energy Commission.

BACKGROUND OF THE INVENTION Most heat exchangers in use today employ a series of tubes to convey a fluid which is placed in indirect heat exchange fluid. another fluid. The tubes are connected at their ends with a tube sheet and one of the heat exchange liquids flows over the outside of the tubes to create a heat exchange between the fluid inside of the tubes and the fluid passing over them.

Whether the fluid which passes over the outside of the tubes is the heating or primary fluid or the heated or secondary fliud, a pressure at the tube sheet is created. It is necessary, therefore, that heat exchangers are constructed so that the tube sheet can resist the internal pressure caused by the fluid flowing over the tubes.

In spite of the fact that rigid construction is necessary to resist the internal pressure on the tube sheet, there are many instances where it is desirable that the tube sheet and the associated tubes can be easily removed from the heat exchanger. Such an example is found in the nuclear field where a primary fluid such as liquid sodium or molten salt is flowed over the outside of the tubes. A pressure is created at the tube sheet and the pressure which can be considerable can also vary due to changes in the flow rate and temperature of the primary fluid. This large inconsistent pressure requires a tube sheet which is secured against movement away from the primary fluid, but which can be easily removed when it is necessary to inspect or to repair the tube section.

The tube section must be removed for repair, for example. when a tube fails. If the secondary fluid is water or steam, the heat exchanger is shut down and the tube section is removed so that the ruptured tube can be plugged to thereby prevent a sodium water reaction when the heat exchanger is put back into service. If the secondary fluid is sodium. it is also desirable that the tube section be quickly removed to allow the ruptured tube to be plugged to prevent intermingling of the primary and secondary sodium. This is necessary because the primary sodium is usually radioactive and safety and health requirements call for a secondary sodium which is not in direct heat exchange with the primary sodium to prevent it from becoming radioactive.

SUMMARY OF THE INVENTION It is an object of the present invention to overcome drawbacks found in the prior art such as those discussed above. Accordingly. a heat exchanger having a tube sheet with primary fluid on one side and secondary fluid on the other which is connected with a bearing surface adjacent to the side of the surface farthest from the tube sheet which is engaged by a plurality of shear blocks which extend outwardly into a slot which is held immovable with respect to the shell so that the shear blocks hold the tube sheet against pressure created by the fluid flowing over the tubes. but which permit the tube sheet and its associated tubes to be easily removed for inspection or repair.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is aside view, partly in section, of a portion of a heat exchanger made in accordance with the present invention;

FIG. 2 is a plan view showing the shear blocks of FIG. I, arranged in proper position with respect to each other to secure the tube sheet and tube section of the heat exchanger; and

FIG. 3 is a side view. partly in section. showing the shear blocks of FIG. I and FIG. 2 in relation to their contiguous elements.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT There is shown in FIG. 1, the upper end portion of a heat exchanger 10 having an outer shell 12 which is generally circular in cross-section with a primary fluid inlet 13 and an outwardly projecting flange 14 at the upper end. The outer shell 12 and the entire heat exchanger 10 is suspended from a vertically extending suspender cylinder 16 which has a flange 18 at its upper end which rests on an annular lip 20 which extends around a hole 22 in a concrete floor 24.

At the lower end of the suspender cylinder 16 is an inwardly extending flange 26 having at its inner marginal portion a bearing surface 28 upon which rests the flange 14. The flange 14 is secured to the flange 26 by a ring 30 which is mounted to the top of the flange 26 and which has an inwardly extending rib 32 which projects into and fits tightly within an annular groove 34 in the outer surface of the flange l4.

Suspended within the outer shell 12 of the heat exchanger 10 is what is commonly called an inner core 40. The inner core includes a tube section comprising a tube sheet 42, a plurality of tubes 44 extending downwardly to a lower tube sheet (not shown). The tube sheet 42 is annular in configuration and encircles a centrally located pipe 48. The purpose of the central pipe 48 is to allow the secondary fluid to flow to the bottom of the heat exchanger so that it can reverse its direction and flow upwardly through the tubes 44 to be heated by primary fluid. It is then collected above the tube sheet 42 to leave by a secondary outlet 49.

A flow shroud 50 encircles the tubes 44 over most of their length. It extends upwardly to a level below the tube sheet 42 so that primary fluid entering at 13 will flow upwardly and over the top of the shroud to then flow downwardly over the tubes 44 and thereby indirectly heat the secondary fluid flowing upwardly in the tubes 44.

The upflow of primary fluid causes some pressure at the lower surface of the tube sheet 42. In addition, variations in temperature and static pressure of fluid entering at 14 can cause variations in the pressure which is exerted by the primary fluid at the lower surface of the tube sheet 42. In designing structure which holds the tube sheet 42 down and against this pressure. it must be borne in mind that it will become necessary, as explained above, to remove the entire core from the outer shell 12 for maintenance and/or inspection. To this end. the entire inner core 40 is suspended from an annular generally vertically extending ring 52 which merges with the inner core just above the tube sheet 42 and which has an outwardly extending flange 54 at its top. The outwardly extending flange 54 rests on an inwardly extending ledge 54 on the flange 14.

Upward pressure on the tube sheet 42 created by the primary fluid is resiste'd by a plurality of shear blocks 60 which extend over an annular bearing surface 61 which is a portion of the top of the flange 54 and extend outward and into an annular slot 62 in the flange 14. As shown in FIG. 3, the flanges 54 and 14 have between them an omega seal 64. This prevents the escape of primary fluid between the flanges l4 and 54. Extending between the flanges l4 and 54 and bridging the shear blocks 60 is a ring 66 which prevents rotation between the flanges l4 and 54. It also provides a secondary seal between those flanges.

The shear blocks 60 are placed annularly around the top of the flange 54 and are alternately positioned with respect to shear blocks 70. The shear blocks 60 are wider at their inner edge portion than they are at their outer edge portion, while the shear blocks 70 are wider at their outer edge portion than they are attheir inner edge portion. With this arrangement. in order to remove the inner core 40 of the heat exchanger 10, it is merely necessary to remove the ring 66 and then move the shear blocks 60 inward. After the shear blocks 60 are moved inward, it is then possible to move the shear blocks 70 inward. When all of the shear blocks have been moved inward far enough to release them from the annular slot 62, the inner core 40 can be moved upward for repair and/or inspection. lnward movement of the shear blocks 60 and 70 is facilitated by the provision of an upwardly extending projection 72 at their inner portions. Tools can grip or strike against these projections and thereby exert the force necessary to move the blocks 60 and 70 inward.

The foregoing describes but one embodiment of the present invention, other embodiments being possible without exceeding the scope of the present invention as defined in the following elaims.

What is claimed is:

l. A heat exchanger comprising:

an outer shell of circular cross-section;

a fluid inlet in said outer shell;

a fluid outlet in said outer shell below said fluid inlet;

an annular slot extending around the inside of said shell adjacent to the top of said shell;

and a portion of each block extending into said slot and the inner edges of said blocks being free of engagement with any structure so that each of said blocks can be moved inward and out of said slot;

whereby said shear blocks prevent said inner core from moving upward but can be moved inward and out of engagement with said slot so that said inner core can be lifted out of said shell.

2. A heat exchanger defined in claim 1 wherein said shear blocks are of two types, said two types being alternately positioned along said surface, one of said types being wider at .the inner edge than the outer edge, the other of said types being wider at the outer edge than at the inner edge, whereby each of said one type may be moved inwardly and subsequently the blocks of the other type may be moved inwardly to permit said inner core to be moved axially and out of said outer shell.

3. The heat exchanger defined in claim 1 further' comprising a ring bridging said blocks and connected with said bearing surface and said shell to prevent relainner core out of said outer shell. 

1. A heat exchanger comprising: an outer shell of circular cross-section; a fluid inlet in said outer shell; a fluid outlet in said outer shell below said fluid inlet; an annular slot extending around the inside of said shell adjacent to the top of said shell; an inner core positioned within said shell, said inner core comprising a tube sheet, a plurality of tubes extending down from said tube sheet so that fluid from said inlet flows over the outside of said tubes and out through said outlet, and an annular bearing surface immovable with respect to said tube sheet, facing upward and disposed adjacent to said slot; and a plurality of shear blocks disposed in a circle with a portion of each block engaging said bearing surface and a portion of each block extending into said slot and the inner edges of said blocks being free of engagement with any structure so that each of said blocks can be moved inward and out of said slot; whereby said shear blocks prevent said inner core from moving upward but can be moved inward and out of engagement with said slot so that said inner core can be lifted out of said shell.
 2. A heat exchanger defined in claim 1 wherein said shear blocks are of two types, said two types being alternately positioned along said surface, one of said types being wider at the inner edge than the outer edge, the other of said types being wider at the outer edge than at the inner edge, whereby each of said one type may be moved inwardly and subsequently the blocks of the other type may be moved inwardly to permit said inner core to be moved axially and out of said outer shell.
 3. The heat exchanger defined in claim 1 further comprising a ring bridging said blocks and connected with said bearing surface and said shell to prevent relative rotation between said inner core and said outer shell.
 4. The heat exchanger defined in claim 1 further comprising an omega seal extending between said bearing surface and said shell.
 5. The heat exchanger defined in claim 1 wherein each of said blocks has an upwardly extending projection on the inner portion thereof so that a force can be exerted on said projection to move said blocks out of said slot to allow for subsequent movement of said inner core out of said outer shell. 